OF THE PALMS. 19 



packed that a powerful blow from a sharp 

 hatchet will often fail to cut it. This inability 

 of expansion in the stems necessarily limits the 

 age of endogenous trees : they die in the end of 

 actual choking : the vessels become so densely 

 impacted, and so obstructed by secretions, that 

 the circulation of the sap is impeded, and the 

 tree languishes and dies. Palms that have 

 begun to be sickly from this cause have been 

 restored to vigour by splitting down the trunk 

 with an axe, which has afforded the needed 

 means of expansion to the compressed vessels. 

 The cells of the soft central portion of the 

 stem are, in many palms, stored with starch, 

 which is of great use as being a reservoir of 

 nutriment for the growth and maturity of 

 the plant. Starch is a very important se- 

 cretion in the vegetable economy, as well as 

 a valuable product for the service of man. 

 It is, in fact, a kind of gum, stored up iu 

 minute bladders, as may easily be seen by a 

 good microscope. These delicate bladders are 

 not acted upon by cold water, but hot water 

 instantly dissolves them, and sets free the gum, 

 which appears to be contained in them in a 

 semi-fluid state ; the reason is thus evident 

 why starch, when once boiled, can never be 

 restored to • its original state and appearance. 



